Don't know enough about Aussie racing so I won't speak out on that.
The other two however: The big ones. Enough cases to support that for Indy. CART eventually went belly up after all once Ganassi Racing went for (and did win) Indy in 2000 and showed the importance Indy still had despite it was share of a nothing special championship to its CART rivals.
How many drivers who did not became Indycar champion stated their season was already a success after winning Indy?
Who won Indy in 1971 and 1972 and who was the Indycar champion that year? (I had to look up one of the answers ands was shocked to find the results because I wasn't aware of a certain achievement.
How many great drivers within the championship with results to boost are hardly remembered while we do know who won Indy that year?
Eddie Cheever a better driver than Michael Andretti?
Enter Roger Penske: His 1983 type PC11 finished second in the 1983 "500" but was replaced by updated 1982 cars shortly after Indy for the remainer of the season since the PC11 refused to work properly. His 1995 type PC24 made one of his drivers finish second in the championship, this despite this driver failing to qualify for Indy! None of the PC24s made the field that year. Which car do you think leaves the worst taste in the mouth with Roger?
I know ther must be more people out here who can bring up similar cases for sportcars and Le Mans, better then I can.
But one thing I do remember: One year both Nissan and/or Mazda entered the full championship with their cars because that was needed to gain automatic entries to Le Mans.
As much as I like both these big events which both are part of what once was my "Grand slam" in racing, I regret that they overpower thei series they are part of so heavily as they do.
(NB: the other two events of my Grand slam were the Monaco GP and the old style Rally de Monte Carlo, when they still had the concentration routes through Europe. By now I don't care for any of the Monte Carlo events anymore)
Henri